Regarding electric/electronic parts such as optical semiconductor apparatuses (LEDs), an optical semiconductor element is sealed with a silicone cured product in order to improve the reliability thereof. While a curable silicone composition in a hydrosilylation reaction is used in order to form this silicone cured product, the silicone cured product obtained by curing the composition has insufficient adhesion to base materials of optical semiconductor elements, package materials, substrates, etc. In particular, silicone cured products, which have less surface tackiness, less adhesion of dust, etc., and high hardness, have insufficient adhesion to base materials.
In order to improve the adhesion of silicone cured products to base materials, the base materials are known to be treated with a primer composition in advance. As this primer composition, for example, a primer composition (see Patent Document 1) comprising an acryl-based polymer, a silanol condensation catalyst, and a silane coupling agent; a primer composition (see Patent Document 2) comprising an organosiloxane oligomer having an epoxy group and a silicon atom-bonded alkoxy group, and an organic solvent; and a primer composition (see Patent Document 3) comprising a silane coupling agent, an organic aluminum compound of a Lewis acid, and an organic solvent are known.
Unfortunately, even these primer compositions problematically have insufficient adhesion. Further, due to miniaturization of LEDs, as well as increases in calorific values caused by high luminance of LEDs, in recent years, peeling or cracking problematically tends to occur between the silicone cured product and base materials, under heat cycles.